Tow with internally incorporated additive



March 1965 J. w. TAMBLYN ETAL 3,173,427

TOW WITH INTERNALLY INCORPORATED ADDITIVE Filed Feb. 5, 1962 Fig;

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TOBACCO SMOKE FLOW F ILAMENTS C'HRRYING EXUDED CRYSTALLINE DEPOSIT Figz TOBACCO SMOKE FLOW F ILAMENT CARRYING EXUDED CRYSTALLINE DEPOSIT JohnW Tamblyn George To ue g INVENTORS BY @W/M/ ATTORNEYS United States Patent Ofiice 3,173,427 TOW WITH ENTERNALLY INCORPORATED ADDITIWE John W. Tamblyn and George P. Touey, Kingsport, Terran,

assignors to Eastman Kodak Company, Rochester, N.Y.,

a corporation of New Jersey Filed Feb. 5, 1962, Ser. No. 171,244 2 Claims. (Cl. 131-298) This invention relates to a textile type tow useful for filter material. In particular, it relates to a new method for producing a cigarette filter tow of substantially parallel fibers containing solid protrusions extending from the surfaces of the fibers into the spaces between the fibers.

Among the wide variety of materials which has been recommended as tobacco smoke filters, one type in particular is ideally suited for this purpose from a manufacturing standpoint. This type is a continuous, crimped, tow material. This type in particular is a continuous, crimped cellulose acetate textile tow described in the several Crawford and Stevens U.S. patents. One reason for its widespread use is the ease and rapidity at which this material can be processed into firm or rigid filter rods on equipment known to the cigarette industry. Thus, for example, a crimped continuous cellulose acetate tow of 5,000 to 20,000 filaments, depending on the thickness of the spun fibers, can be bloomed out, sprayed with a non-volatile liquid plasticizer type of bonding agent, recompacted and pulled through a rod forming and paper wrapping device to produce 90 mm. filter rods at the rate of several hundred per minute. Such rods become quite firm on standing for a period of time.

Although continuous crimped textile tow is a useful filter material from a processing standpoint as explained above, it has what perhaps may be considered a certain disadvantage from the standpoint of its ability to remove the tiny nicotine and tar particles from cigarette smoke. This aspect is the somewhat parallel relationship of many of the smooth fibers which constitute the filtering element. As a result, a certain amount of the nicotine and tar particles may be capable of passing between the longitudinally aligned smooth fibers without touching them. These particles, therefore, are not trapped. One method which has been suggested for circumventing this difiiculty of a filter containing longitudinally aligned smooth fibers is to use a very fine denier fiber in the preparation of the tow. This would mean that it would require a considerably larger number of fibers in the tow to fill the filter to the desired circumference of a cigarette, thus giving a higher surface area and a much smaller space between the parallel fibers. Such an approach, however, gives a filter tip which may have a higher pressure drop (high resistance to the passage of air through the filter).

Another method which has been suggested of producing a textile tow type of filter which is highly effective for the removal of nicotine and tar particles and yet does not produce an excessively high pressure drop is to dust the tow with certain harmless powders such as starch powders or powders of cellulose or cellulose derivatives at some point along the assembly which processes it into a filter. This produces, in effect, an irregular surface on the substantially parallel fibers. The particles of the powdered additive function as bumps or protrusions which extend into the spaces between the fibers in the finished filter rod. These protrusions make the path of the smoke particles through the filter more difiicult and part of the nicotine and tar particles which might channel through the filter are impinged on these protrusions.

3,173,427 Patented Mar. 16, 1965 Although the addition of powdered additives improves a textile tow type of cigarette filter, this approach has some problems from the standpoint of the application of the additive to the tow. Frequently, the powder is dusted on the tow or suspended in a liquid and sprayed on the tow. The dusting technique requires a dusting booth with suitable precautions taken to prevent dust explosions. Also, the dusting procedure presents problems on the part of the operator since it is difficult to restrict the dust to the dusting booth. This leads to maintenance and clean-up problems. When the powder is suspended in a liquid (for example the plasticizer or plasticizer and diluent used to harden a cellulose acetate tow filter) and sprayed on the tow the dusting problems are eliminated. However, it may add to expense to spray on highly concentrated suspension of powder in a liquid from the conventional spray guns. When the powder in the slurry or suspension is quite viscous. This condition has a tendency to clog some spray guns. It has also been found that some methods produce a filter which allows traces of the additive to sift out when it is tapped. This does not produce a favorable impression on the smoker.

Therefore, it seems apparent that the development of a new tow which overcomes or minimizes at least some of the aforementioned problems represents a highly desirable result. After extended investigatioln, we have discovered a new and unobvious tow material as will be described in detail hereinafter.

One object of this invent-ion is to provide an entirely new technique for producing solid protrusions on the surfaces of fibers destined for use as tobacco smoke filters. Another object is to provide a method for producing protrusions on the surfaces of fibers in a textile tow type of cigarette filter material without having to treat the tow with a dust or a liquid suspension of a powder. Another object is to disclose a method for producing protrusions on the surfaces of fibers in a textile tow type of cigarette filter material without having to spray materials on the tow. Still another object is to provide a new type of cigarette filter materiala spun textile fiber containing tiny solid particles (protrusions) on its surface, said protrusions being formed by the gradual exudation of a plastic material from within the fiber. Other aspects will appear hereinafter.

In the broader aspects of this invention, these objects are accomplished in the following manner: Certain crystallizable types of compounds are incorporated into a fiber forming polymeric substance, which is then melted or dissolved in a suitable solvent and spun into fibers in the conventional manner. After the fibers are formed, these special additives gradually exude to the surface of the fibers whereupon they crystallize forming rough irregular protrusions on the fibers. It is these protrusions of solid particles on the surface of the smooth fibers which cause the fibers to be a more effective filter when they are aligned in a substantially parallel arrangement as in the case of tobacco smoke filter tow.

The type of fiber forming polymeric substance can be chosen from any of the known types of compounds which, when melt spun or spun from an organic solvent, produce fibers of suflicient strength and stretch to be converted into filter tow. Examples of the types of melt spinnable polymeric substances are polyethylene, polypropylene, and the various polyesters and polyamides. Examples of the solution spinnable polymeric substances are the various organic solvent soluble cellulose derivatives and vinyl esters and ethers. The polyethylene and polypropylene fiber forming polymers are good representations of the melt spinnable polymeric substances which can be used. With regard to the solution spinna- 3 ble type, cellulose acetate is a representative polymer. In order to illustrate this invention, therefore, only examples involving polyethylene and cellulose acetate fibers will be used. However, it is to be understood that other fiber forming spinning dopes can be used without departing from the scope of this invention.

The type of exuding additive can vary considerably with regard to its chemical composition. A principal requirement is the additive should be soluble or dispersible in the fiber forming melt or solution as it is spun and be capable of migrating to the surface of the spun fibers and crystallizing or solidifying to form an exudate on the surface in the form of fine particles. ther requirements are the additives preferably are heat stable and substantially water insoluble. They also preferably have a, melting point not lower than 40 C. This temperature approaches the maximum temperature developed in cigarette smoke as it reaches the smokers mouth.

Examples of compounds which meet these requirements are the following:

(1) l-lighmolecular Weight solid, fatty acids, alcohols, and

esters Stearie acid, stearyl alcohol,- glycerol inonostearate, 'acetylated glycerol mon-o'stearate, hydrogenated castor oil, palmitic acid, glycerol mon'opalmitate (2) Naturally occurring waxes- Beeswax, Japan wax, caranauba wax, etc.

(3) High-boiling organic plasticizers which are crystalline solids at 40 C. or above (a) Phthalic acid and terephthalic acid esters: Diphenyl phthalate, dicyclohexyl phthalate, dibenzyl phthalate, dinaphthyl phthalate, dihexadecyl phthalate, monobenzyl phthalate, monophenyl phthalate, monocyclohexyl phthalate, dimethyl terephthalate, diethyl phthalate, diisopropyl terephthalate, diisobutyl terephthalate, diphenyl terephthalate, dimethyl terephthalate (b) Benzoic acid esters: Phenyl benzoate, ethylene glycol dibenzoate, resorcinol monobenzoate (c) Salicyclic acid esters: Acetyl salicyclic acid trisalicylin, phenyl salicylate, acetyl phenyl salicylate, benzyl phenyl salicylate, methoxyphenyl salicylate (d) Miscellaneous: Dimethyl tartrate, trimethyl citrate, diphenyl succinate The amount of crystalline solid which is dissolved or dispersed in the spinning dope to produce a more effective filter tow can vary between 5 and 40% based on the combined weight of the spun yarn and additive. In the case of a filter consisting of fine denier filaments (0.6 to 2 denier per filament) only 515% of the additive is required. This is because in such a filter the fibers are closer together and therefore it needs less protrusions jutting out between fibers to aid in the impingement of the tar and nicotine particles. Also, the pressure drop of a filter of such fine denier fibers is already higher than a filter from larger denier filaments and overloading it with additional material might make the draw of the filter too ditficult. In the case of the filters prepared from the heavier fibers (4-16 denier per filament) it is apparent that more protrusions into the spaces between the fibers are desirable. Usually an amount between and 40% is useful for such filters.

For further assisting in a better understanding of this invention reference may be made to the attached drawing forming a part of the present application.

In this drawing, FIG. 1 is a diagrammatical illustration on a considerably enlarged or magnified scale of a segment of a plurality of crimped, continuous filaments carrying crystalline particles on the surface of the filaments, which particles have exuded in accordance with the present invention.

FIG. 2 is a diagrammatical illustration also on a considerably large or magnified scale of a single crimped filament carrying particles on the surface of the filament in accordance with the present invention. In further def tail and referring to FIG. 1, the plurality of individual filaments are shown at 1, 2 and 3. These filaments are Substantially continuous, only a segment of these continuous filaments making up the tow being illustrated in the figure. These filaments contain crimp as illustrated at points 4 and 5, for example. The filaments carry the exuded cwstalline additive of the present invention as, for example, indicated at 6 and 7. Several thousand of these filaments making up the tow would be intermingled in a bundle comprising the tow.

Reference is now made to FIG. 2 wherein a segment of a single continuous filament is illustrated. This figre shows in more detail some of the features referred to above. For example, in this figure 11 designates the filament. The peak of a crimp is indicated at area 12. The exuded crystalline additive carried by the surface of the filament is indicated at, for example, 13 and 14.

Having descri" ed our invention somewhat generally, further details will be apparent from the following examples illustrating our preferred embodiments. In these examples we have limited the exuding additives to a few representations of the groups listed above. In the smoking tests in the examples the same brand of king size cigarette was used. It was a brand representing a typical domestic type of cigarette tobacco.

EXAMPLE I Cellulose acetate yarn containing an exuding organic acid ester A 5 denier per filament yarn was spun from a dope consisting of 28 parts cellulose acetate (39.6% acetyl), 5 parts diphenyl succinate, and 68 parts acetone. The yarn was then converted to a continuous crimped (l8 crimps per inch) tow of 12,000 filaments. The tow was pulled over a series of air jets which bloomed it out to a width of 12 inches and While in this spread out condition it was sprayed on both sides with glycerol triacetate plasticizer. This liquid plasticizer is useful as a hardening agent for cellulose acetate filters. The tow was then pulled back together in the form of a rope or cord and led through a device which paper wrapped it into the form of a continuous rod with a circumference equal to that of a standard cigarette. The rods were cut into 15 mm. filter tip lengths and stored at room temperature for a period of one week. During this time several of the 15 mm. filters were opened and observed under the microscope. After the first day the fibers of the filters were still smooth. After the second day a few crystals of diphenyl succinate were visible on the surface of the fibers. After the fourth day the fiber surfaces were covered with minute crystal protrusions of the solid exudate. Analysis of some of the 15 mm. tips showed that they consisted of 78% cellulose acetate, 14% diphenyl succinate and 8% glycerol triacetate. These values are based on the total weight of the filter without the paper wrapper.

Ten of the four day old tips were placed on king size cigarettes which had been shortened by 15 mm. to compensate for the length of the filter. These cigarettes were smoked to butt lengths of 30 mm. on an automatic smoking machine which produced a 35 ml. puff of 2 seconds duration at the rate of 1 puff per minute. The smoke which passed through the filtered cigarettes was collected and analyzed for its nicotine and tar content.

Another yarn of 5 denier per filament was spun from a dope consisting of 30 parts cellulose acetate (39.6% acetyl) and 70 parts acetone. This yarn which contained no internally incorporated additive was then converted to a continuous crimped (18 crimps per inch) tow of 14,000 filaments. This tow was sprayed with glycerol triacetate and converted into cigarete filters in the manner described above. The 15 mm. filters consisted of 91% cellulose acetate and 9% glycerol triacetate bonding agent. These values were based on the total weight of the filter without the paper.

5 Ten of the 15 mm. tips were placed on king size cigarettes which had been shortened by 15 mm. These cigarettes were smoked to but lengths of 30 mm. on the automatic smoking machine. The smoke which passed through the filtered cigarettes was collected and analyzed for its nicotine and tar content.

As a control ten of the unshortened king size cigarettes were smoked on the automatic machine to butt lengths of 30 mm. The smoke which passed through these unfiltered cigaretes was analyzed for nicotine and tar content.

Av. Mg. Mg. Pressure Tar Nicotine Filter (15 mm.) Drop 1 From From (10 Ciga- 1O Ciga- 10 Cigarettes) rettcs rettes No filter (control) 3.1 170 28. 5 Cellulose acetate fibers without exuding additive 3. 9 142 23. 8 Cellulose acetate figers with exuding internally incorporated additive 4. 118 19. 6

1 Pressure drop expressed as inches of water at an air flow rate through the cigarette of 17.5 ml./sec.

EXAMPLE II Polyethylene yarn containing an exuding high molecular weight alcohol A mixture of 20 parts stearyl alcohol and 80 parts polyethylene was heated to 150 C. whereupon both components melted. This hot melt was rapidly agitated whereupon all of the stearyl alcohol dispersed in polyethylene. It was then solidified by cooling back to room temperature and pelletized for melt spinning. Good quality yarn was obtained by melt spinning these pellets at an extrusion temperature of 290 C. The yarn was drafted and converted to a crimped continuous tow consisting of 14,00 filaments of denier per filament and containing 16 crimps per inch. The tow was pulled over a series of air jets which bloomed it out to a width of 12 inches. While in this spread condition it was sprayed lightly on one side with a 50% latex emulsion of polyvinyl acetate (bonding agent) and pulled back together in the form of cord. It was then led through a device which paper wrapped it into a continuous rod with the circumference the size of a cigarette. The rod was then cut into 15 mm. lengths and these were stored overnight over calcium chloride. Analyses of the dry rigid tips revealed that they consisted of 76.8% polyethylene, 19.2% stearyl alcohol, and 4% polyvinyl acetate bonding agent. These values are based on the total weight of the filter without the paper wrapper.

Periodic microscopic observation of several of the opened filter tips revealed that it required a period of 3 days for the stearyl alcohol to exude to the surface of the polyethylene fibers forming crystal like protrusions. Ten of the 3 day old tips were placed on king size cigarettes which had been shortened by 15 mm. These cigarettes were smoked to butt lengths of 30 mm. on the auto matic smoking machine. The smoke which passed through the filtered cigaretes was collected and analyzed for nicotine and tar content.

Filters (15 mm.) were prepared from a continuous crimped (16 crimps per inch) tow of polyethylene fibers without the stearyl alcohol. This tow contained 20,000

6 filaments of 5 denier per filament. The method of blooming out the tow, applying the bonding agent and then converting the tow into 15 mm. filters was identical to that described above. Analyses of the dry, rigid tips revealed that they consisted of polyethylene and 5% polyvinyl acetate bonding agent based on their weight without the paper wrapper.

Microscopic observation of several of the opened filter tips after ,a storage time of one week showed that the substantially longitudinally aligned fibers were smooth. Ten of the tips were placed on king size cigaretes which had been shortened by 15 mm. These cigarettes were smoked to butt lengths of 30 mm. on the automatic smoking machine. The smoke which passed through the filtered cigarettes was analyzed for nicotine and tar content.

These values when compared with those obtained from v the unfiltered cigarette (Example I) show that the polyethylene filter removed 19% more tar and 18% more nicotine than the 15 mm. length of tobacco it replaced. The polyethylene filter containing the exuding additive removed 32% more tar and 30% more nicotine than the 15 mm. length of tobacco it replaced. The filter without the additive contained sufiiciently more polyethylene fibers to make its pressure drop about equal to that of polyethylene-stearyl alcohol filter. This, therefore, illustrates that the addition of more fibers to the control filter to adjust its pressure is not as eifective as adding an exuding compound to the polyethylene.

It is thought apparent from the foregoing that we have provided a new tow having a roughened surface which has special utility as shown for making filter elements. Such tow with internally incorporated additive is thought to have advantages over tow, the surface of which has added externally applied powder or the like in that the present invention provides a product more permanent and easier to manufacture. As indicated above, the new tow of the present invention may be lubricated in ways described in the prior art, crimped, packaged in a bale or otherwise handled. Preferably, as set forth in the above examples, the crimped tow may be manufactured directly into tobacco smoke filter elements.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

We claim:

1. An intermediate material useful in the manufacture of tobacco smoke filter elements comprised of a wrapped bundle of continuous fibers of a denier/ filament of 06-15, said fibers having rough, irregular protrusions of fine, solid particles of crystalline material obtained from having incorporated into the fiber-forming polymeric substance from which said fibers are extruded an internally incorporated organic crystallizable compound compatible with said polymeric substance, said compound being heatstable, substantially water-insoluble and non-oily with a melting point of not less than about 40 C. characterized in that it is capable of migrating to the surface of the extruded fibers over a period of several days by exuding to form said rough, irregular protrusions which become visible under a microscope as minute crystal protrusions of solid exudate after about four days, said compound being one of the members of the reacting compounds and reaction products of the reaction between an alcohol and an organic acid to form an ester, said compound havnig been incorporated in said polymeric substance in an amount sufficient within the range of 54()% to migrate to the surface of the extruded fibers to form said rough, irregular protrusions of solid crystalline material, the extruded fibers having been stored prior to use as said intermediate for at least said four days so that said migration has occurred whereby said compound has solidified on the surface of the fibers in the form of said rough, irregular protrusions.

2. The intermediate of claim 1 wherein the organic crystallizable compound is selected from the group consisting of (1) high molecular weight solid, fatty acids, alcohols, and esters selected from the group consisting of stearic acid, stearyl alcohol, glycerol monostearate, acetylated glycerol monostearate, hydrogenated castor oil, palmitic acid, and glycerol monopalmitate and (2) highboiling organic plasticizers which are a crystalline solid at about 40 C. for above selected from the group consisting of diphenyl phthalate, dicyclohexyl phthalate, dibenzyl phthalate, dinaphthyl phthalate, dihexadecyl References Cited in the file of this patent UNITED STATES PATENTS 2,036,861 Dreyfus Apr. 7, 1936 2,079,108 Dreyfus et al May vA, 1937 2,166,739 Karplus Ju1y 18, 1939 2,166,740 Karplus July 18,1939 2,578,664 Beery et al. Dec. 18, 1951 2,742,371 Albus et al Apr. 17, 1956 2,881,770 Touey Apr. 14, 1959 2,904,050 Kiefer et a1 Sept. 15, 1959 3,026,226 Touey et al Mar. 20, 1962 

1. AN INTERMEDIATE MATERIAL USEFUL IN THE MANUFACTURE OF TOBACCO SMOKE FILTER ELEMENTS COMPRISED OF A WRAPPED BUNDLE OF CONTINUOUS FIBERS OF A DENIER/FILAMENT OF 0.6-15, SAID FIBERS HAVING ROUGH, IRREGULAR PROTRUSIONS OF FINE, SOLID PARTICLES OF CRYSTALLINE MATERIAL OBTAINED FROM HAVING INCORPORATED INTO THE FIBER-FORMING POLYMERIC SUBSTANCE FROM WHICH SAID FIBERS ARE EXTRUDED AN INTERNALLY INCORPORATED ORGANIC CRYSTALLIZABLE COMPOUND COMPATIBLE WITH SAID POLYMERIC SUBSTANCE, SAID COMPOUND BEING HEATSTABLE, SUBSTANTIALLY WATER-INSOLUBLE AND NON-OILY WITH A MELTING POINT OF NOT LESS THAN ABOUT 40*C. CHARACTERIZED IN THAT IT IS CAPABLE OF MIGRATING TO THE SURFACE OF THE EXTRUDED FIBERS OVER A PERIOD OF SEVERAL DAYS BY EXUDING TO FORM SAID ROUGH, IRREGULAR PROTRUSSIONS WHICH BECOME VISIBLE UNDER A MICROSCOPE AS MINUTE CRYSTAL PROTRUSIONS OF SOLID EXUDATE AFTER ABOUT FOUR DAYS, SAID COMPOUND BEING ONE OF THE MEMBERS OF THE REACTING COMPOUNDS AND REACTION PRODUCTS OF THE REACTION BETWEEN AN ALCOHOL AND AN ORGANIC ACID TO FORM AN ESTER, SAID COMPOUND HAVING BEEN INCORPORATED IN SAID POLYMERIC SUBSTANCE IN AN AMOUNT SUFFICIENT WITHIN THE RANGE OF 5-40% TO MIGRATE TO THE SURFACE OF THE EXTRUDED FIBERS TO FORM SAID ROUGH, IRREGULAR PROTRUSSIONS OF SOLID CRYSTALLINE MATERIAL, THE EXTRUDED FIBERS HAVING BEEN STORED PRIOR TO USE AS SAID INTERMEDIATE FOR AT LEAST SAID FOUR DAYS SO THAT SAID MIGRATION HAS OCCURRED WHEREBY SAID COMPOUND HAS SOLIDIFIED ON THE SURFACE OF THE FIBER S IN THE FORM OF SAID ROUGH, IRREGULAR PROTRUSSIONS. 